Tensioning Roller or Winder Device

ABSTRACT

The chain or belt tensioning roller or winder device is provided with a rolling bearing  14  comprising an inner ring  30,  an outer ring  32  and at least one row of rolling elements  34  mounted between the rings, with a pulley  12  overmoulded onto the outer ring and with a fixing screw  18  axially immobilized with respect to the rolling bearing. 
     The device comprises a sleeve  16  overmoulded inside the bore of the inner ring and provided with a through-bore  16 d for mounting the fixing screw  18.  The sleeve is provided with means of axially retaining the fixing screw  18  inside the through-bore of the sleeve  16.

The present invention relates to the field of tensioning rollers or winders designed to collaborate with a chain or belt, for example a timing belt of a motor vehicle internal combustion engine.

Such rollers are generally used to keep the belt or chain tension always within a determined range or to make a local alteration to the path followed by this belt or chain. In the case of winding rollers, the pulley is mounted for rotation on a spindle via a rolling bearing, the roller then being fixed directly or indirectly to the engine block or to a part of the tensioning roller device, for example an articulated arm or an eccentric.

In many types of belt or chain rollers of the prior art, the pulley is overmoulded onto the outer ring of the rolling bearing which is itself mounted directly on a fixing spindle attached to the engine block. Thus, the diameter of the bore in the inner ring has to be adapted to suit the radial dimension of the spindle used by the motor vehicle manufacturer. That runs counter to the practice of standardizing the rolling bearings used for such applications.

Document DE-A1-100 35 488 describes a mounting device for a belt pulley comprising a sleeve tube provided with a flange that forms a spacer piece for the inner ring of the rolling bearing, and with a retaining tube collaborating with the sleeve tube to press against the inner ring axially on the opposite side to the flange.

This solution has the disadvantage of entailing the use of two distinct elements in addition to the assembly formed of the rolling bearing and of the pulley, something which is disadvantageous for transporting, handling and fitting these elements.

Document FR-B1-2 758 375 describes a tensioning roller comprising a pivoting body, a rolling bearing mounted on the said body, and a bushing made of metal to accept the fixing spindle intended to be attached to the engine block. The pivoting body is obtained by overmoulding a synthetic material in the bore of the rolling bearing and over the exterior surface of the bushing.

Again, document DE-U1-298 05 581 discloses a tensioning roller comprising a rolling bearing, a pulley overmoulded on the outer ring of the rolling bearing, and a filler piece overmoulded in the bore of the inner ring of the rolling bearing and on a fixing spindle.

The tensioning rollers described in these two documents have the major disadvantage that they cannot be easily adapted to suit the size of the spindle or of the fixing screw designed to be mounted on the engine block.

It is therefore an object of the present invention to overcome these disadvantages.

More particularly, the present invention sets out to provide a tensioning roller device that is particularly easy to manufacture, to fit, and is of small size.

A further object of the present invention is to provide a device that can be easily and economically adapted to suit the size of the fixing screws that are to be used by the motor vehicle manufacturers.

To this end, the chain or belt tensioning roller or winder device is provided with a rolling bearing comprising an inner ring, an outer ring and at least one row of rolling elements mounted between the rings, with a pulley overmoulded onto the outer ring and with a fixing screw axially immobilized with respect to the rolling bearing. The device comprises a sleeve overmoulded inside the bore of the inner ring and provided with a through-bore for mounting the fixing screw. The sleeve further comprises means for axially retaining the fixing screw inside the through-bore of the sleeve.

Thus, various tensioning roller devices can be produced in a particularly economical manner using rolling bearings of the same size. Specifically, the bore of the pulley is adapted to suit the diameter of the fixing screw by adapting the sleeve which is advantageously made of a synthetic material. The use of such a sleeve makes it particularly simple to fit. The existence of the through-bore in the sleeve allows the use of a standard fixing screw or spindle. Furthermore, having a sleeve provided with means of axially retaining the fixing screw means that it is possible to obtain an individual assembly that can be stored, transported and handled without the risk of its component parts becoming detached, and this can be done without the need for additional separate elements. Specifically, the sleeve itself comprises the retaining means which may advantageously be formed as one piece therewith.

Advantageously, the fixing screw is in direct contact with the through-bore.

In one embodiment, the axial-retention means comprise a threaded portion able to collaborate with a threaded portion of the fixing screw.

In one embodiment, the outside diameter of the sleeve is smaller than the inside diameter of a frontal radial surface of the inner ring.

Thus, after the sleeve has been overmoulded, the rolling bearing is a bearing that has an inner ring with an entirely unencumbered radial frontal surface. This makes mounting elements against the said frontal surface of the ring, for example an axial end stop member, far easier.

In one embodiment, frontal radial surfaces of the sleeve are set back from or flush with frontal radial surfaces of the inner ring.

Advantageously, the sleeve comprises, at one axial end, a spacer piece which bears axially against the inner ring.

In one embodiment, the sleeve is an eccentric sleeve.

The device may also comprise a protective end plate mounted on the sleeve. The protective end plate advantageously comprises a tubular axial portion fitted into a large-diameter portion of the bore of the sleeve. The end plate may be mounted pressing against a frontal radial surface of the inner ring.

In one embodiment, the pulley and the sleeve are made of one and the same synthetic material.

The present invention will be better understood from studying the detailed description of some embodiments taken by way of nonlimiting examples and illustrated by the attached drawings in which:

FIG. 1 is a front elevation of a roller for a belt or chain according to a first embodiment of the invention,

FIG. 2 is an axial section on II-II of FIG. 1,

FIG. 3 is an axial section through a roller according to a second embodiment of the invention,

FIG. 4 is an axial section through a roller according to a third embodiment of the invention,

FIG. 5 is a view of a detail of FIG. 4,

FIGS. 6 to 8 are axial sections through a roller according to fourth, fifth and sixth embodiments of the invention,

FIGS. 9 and 10 are front elevations of a roller according to a seventh embodiment of the invention,

FIG. 11 is a section on XI-XI of FIG. 10,

FIG. 12 is a front elevation of a roller according to an eighth embodiment of the invention, and

FIG. 13 is a roller in section on XIII-XIII of FIG. 12.

As may be seen in FIGS. 1 and 2, the roller referenced 10 overall comprises a pulley 12, a rolling bearing 14 of axis 20, an annular sleeve 16 and a fixing screw 18 coaxial with the axis 20.

The pulley 12 comprises an outer part 22 that offers an exterior surface intended to collaborate with a belt or chain (not depicted), an axial interior part 24 and a radial annular intermediate portion 26 connecting said parts. The outer 22 and inner 24 parts are coaxial with the axis 20. The inner part 24 has a bore 24 a equipped with annular ribs 28 and axially delimited by two lateral radial surfaces 24 b and 24 c.

The rolling bearing 14 comprises an inner ring 30, an outer ring 32, two rows of rolling elements 34 and 36 arranged in parallel planes and held respectively in position by cages 38 and 40, and two seals 42 and 44.

The inner ring 30 comprises an outer surface 30 a of revolution in which there have been formed raceways for the rolling elements 34 and 36, and grooves to provide contact with lips of the sealing members 42 and 44. The inner ring 30 also comprises a bore 30 b in contact with the sleeve 16 delimited by two lateral frontal radial surfaces 30 c and 30 d. The cages 38 and 40 keep the rolling elements 34 and 36 uniformly circumferentially spaced. The outer 32 and inner 30 rings are respectively one-piece rings.

The outer ring 32 is provided with a bore 32 a in which there have been formed raceways for the rolling elements 34 to 36 and grooves into which the sealing members 42 and 44 are fitted. The sealing members 42 and 44 provide a static seal against the rotating outer ring 32 and a dynamic seal against the non-rotating inner ring 30. The outer ring 11 also comprises an outer surface 32 d and frontal radial surfaces 32 b and 32 c axially aligned with the radial surfaces 30 c and 30 d. Annular grooves 46 are formed from the outer surface 32 d of the outer ring 32 to complement the shape of the ribs 28 projecting from the bore 24 a of the pulley 12.

The pulley 12 is overmoulded on the outer ring 32. This results in excellent cohesion between these two components, particularly at the annular grooves 34 of the outer ring 32 which the molten plastic enters to form the annular ribs 28 of the pulley 12 through complementary shaping.

The sleeve 16, of annular overall shape with axis 20, has an exterior surface 16 a which is a cylinder of revolution, two lateral frontal radial surfaces 16 b and 16 c, and a cylindrical through-bore 16 d in contact with the screw 18. The bore 16 d or central opening passes axially right through the sleeve 16 and opens onto the surfaces 16 b and 16 c.

The sleeve 16 is overmoulded in the bore 30 b of the inner ring 30. This then provides excellent cohesion between these two components. Although in the exemplary embodiment illustrated, the bore of the inner ring 30 is a plane bore, it will be appreciated that it might be possible to provide annular or helical grooves in the said bore facing radially towards the sleeve 16 so as to obtain annular or helical ribs of complementing shapes as the molten plastic enters them.

The sleeve 16 has an axial dimension smaller than that of the ring 30, and is arranged in such a way that the frontal radial surfaces 16 b, 16 c are set back from the frontal radial surfaces 30 c, 30 d of the inner ring. The outside diameter of the sleeve 16 is smaller than the inside diameter of the frontal radial surfaces 30 c, 30 d of the inner ring. The sleeve 16 therefore leaves the said radial surfaces 30 c, 30 d completely uncluttered so that they can be used as reference surfaces and come to bear against any other radial surface.

Advantageously, the pulley 12 and the sleeve 16 are overmoulded on the rolling bearing 14 in one and the same manufacturing mould, preferably using the same synthetic material, so as to obtain an economical roller 10 that requires a low number of manufacturing operations. However, as an alternative, a different synthetic material could be provided for the sleeve 16, for example a material that is more flexible than that used for the pulley 12 and that has good vibration-damping characteristics.

The screw 18 for its part has a head 18 a and a shank that has a plane portion 18 b near the head and a threaded portion 18 c at the opposite end from the said head. The threaded portion 18 c which projects axially with respect to the pulley 12 can be inserted into a tapped hole created in a component intended to support the roller 10. Axially on the opposite side, there is a washer 50 positioned between the head 18 a and the frontal radial surface 30 d of the inner ring 30 left clear by the sleeve 16. The sleeve 16 is advantageously used to form a means of axially retaining the fixing screw 18. For this, the screw 18 is designed to be a fairly close fit in the bore 16 d of the said sleeve. This class of fit is designed to ensure that the two elements are axially secured to one another with no risk of coming apart while the device is being stored, transported and handled.

The embodiment illustrated in FIG. 3, in which elements that are identical bear the same references, differs only in that the bore 16 d of the sleeve 16 is enlarged so that a larger-diameter fixing screw 18 can be fitted. The close fit between the sleeve 16 and the fixing screw 18 is, however, maintained. Thus, the sleeve 16 can be used to adapt the same type and size of rolling bearing 14 to suit the various different diameters of fixing screw 18. One and the same type of rolling bearing can thus be used for several types of roller 10.

The embodiment illustrated in FIGS. 4 and 5, in which elements that are identical bear the same references, differs from the first embodiment in that the sleeve 16 comprises, near the radial frontal surface 16 b, an annular threaded portion 52 extending radially inwards and collaborating with the threaded portion 18 c of the fixing screw 18 so as to provide axial retention of the screw inside the sleeve 16.

By way of an alternative, this threaded portion 52 could be replaced by one or more pegs projecting radially inwards.

The embodiment illustrated in FIG. 6, in which elements that are identical bear the same references, differs from the first embodiment in that the sleeve 16 has an axial dimension equal to the inner ring 30. The frontal radial surfaces 16 b and 16 c are respectively aligned with or flush with the frontal surfaces 30 c and 30 d of the inner ring 30. The sleeve 16 does, however, leave the said frontal radial surfaces 30 c and 30 d uncluttered. In this embodiment, the roller 10 has no thrust washer for the head 18 a of the screw, the said head coming to bear directly against the frontal surface 16 c of the sleeve 16.

The embodiment illustrated in FIG. 7 in which elements that are identical bear the same references differs from the first embodiment in that the sleeve 16 has an increased axial length and projects axially from the frontal surface 30 c of the inner ring 30. However, the sleeve 16 leaves the said frontal radial surface uncluttered. It has an annular spacer piece 54 that bears against the said surface 30 c of the inner ring 30. The spacer piece 54, advantageously made of metal, is overmoulded on the outer surface 16 a of the sleeve 16. It is advantageously placed in the mould used to manufacture the roller 10 at the same time as the bearing 14, the overmoulding of the pulley 12 and of the sleeve 16 yielding a non-dissociable rolling-bearing/sleeve/spacer-piece assembly.

The embodiment illustrated in FIG. 8 in which elements that are identical bear the same references differs from the first embodiment in that the sleeve 16 comprises, at each axial end of the bore 16 d, two larger-diameter portions 56, 58. The sleeve 16 has a stepped bore 16 d. The roller 10 also has a protective end plate 60, advantageously made of sheet metal, and adopting the form of a cup of annular overall shape. The end plate 60 has an annular axial portion 60 a fitted inside the larger-diameter portion 58 of the bore 16 b to allow the fixing screw (not depicted) through. The said screw can be mounted with a slight clearance fit in the portion 60 a so as to hold the assembly together. The axial portion 60 is extended radially outwards at a free end by a radial portion 60 b that comes to bear against the frontal surface 30 c of the inner ring 30 and that extends into the vicinity of the interior portion 24 of the pulley 12. The radial portion 60 b is extended axially, at its large-diameter edge towards the pulley 12, by an axial portion 60 c situated radially in close proximity to the interior portion 24 and thus forming a seal on account of the narrowness of the passage.

The embodiment illustrated in FIGS. 9 to 11 in which elements that are identical bear the same references differs from the first embodiment in that the roller 10 comprises an eccentric sleeve 62, of axis 64 that is offset radially with respect to the axis 20 of the rolling bearing 14. The eccentric sleeve 62 has a cylindrical exterior surface 62 a in contact with the bore 30 b of the inner ring 30, two lateral frontal radial surfaces 62 b and 62 c, and a through-bore 62 d in which to mount the screw 18. The radial surface 62 b is set back from the frontal surface 30 c of the inner ring 30. The sleeve 62 is overmoulded in the bore 30 b of the inner ring 30.

The eccentric sleeve 62 comprises, at one axial end, a radial flange 66 comprising the radial surface 62 c and coming to bear against the radial surface 30 d on the inner ring 30. The head 18 a of the screw 18 bears against the radial surface 62 c axially on the opposite side to the inner ring 30. The flange 66 has a hexagonal overall shape so that a correspondingly shaped spanner can be used to perform manual adjustment of the angular position of the eccentric sleeve 62 and therefore of the tension in the belt or chain. Of course, this adjustment is performed before the fixing screw 18 is tightened.

The embodiment illustrated in FIGS. 12 and 13 differs from the embodiment previously described in that the radial flange 66 is of cylindrical overall shape and has two cylindrical recesses 68 open at both ends so that the belt or chain tension can be adjusted using a pin spanner.

In the embodiments illustrated in FIGS. 6 to 13, the sleeve 16 is also given a tolerance that makes it possible to obtain a close fit between it and the fixing screw 18 which fit is close enough to ensure axial retention of the said screw.

By virtue of the invention, roller devices that can be adapted to suit various diameters of screw are thus produced economically using the same rolling bearings. Specifically, the pulley bore size is adapted to suit the diameter of the screw through the agency of the sleeve which is made of plastic. Furthermore, the sleeve provides axial retention for the fixing screw or for other elements such as a spacer piece or protective end plate which are designed to bear against one of the rings of the rolling bearing. 

1. A tensioning roller or winder device comprising: a rolling bearing including an inner ring, an outer ring and at least one row of rolling elements disposed between the inner and outer rings, a pulley overmoulded onto the outer ring, a fixing screw axially immovable with respect to the rolling bearing, and a sleeve overmoulded inside the bore of the inner ring and having a through-bore configured to receive the fixing screw, the sleeve having means for axially retaining the fixing screw inside the through-bore of the sleeve.
 2. The device according to claim 1, wherein the fixing screw directly contacts the through-bore.
 3. The device according to claim 1, wherein the axial-retention means include a threaded portion configured to engage with a threaded portion of the fixing screw.
 4. The device according to claim 1, wherein an outside diameter of the sleeve is lesser than an inside diameter of a frontal radial surface of the inner ring.
 5. The device according to claim 1, wherein the sleeve and the inner ring each have frontal radial surfaces, the sleeve frontal radial surfaces being one of spaced from and flush with the inner ring frontal radial surfaces.
 6. The device according to claim 1, wherein the sleeve has an axial end and a spacer piece located at the axial end, the spacer piece being configured to bear axially against the inner ring.
 7. The device according to claim 1, wherein the sleeve is an eccentric sleeve.
 8. The device according claim 1, further comprising a protective end plate mounted on the sleeve.
 9. The device according to claim 8, wherein the sleeve through-bore has a large-diameter portion and the protective end plate includes a tubular axial portion fitted into the sleeve through-bore large-diameter portion.
 10. The device according to claim 8, wherein the protective end plate is configured to press against a frontal radial surface of the inner ring.
 11. The device according to claim 1, wherein the pulley and the sleeve are each formed of a same, synthetic material. 